174PH

174PH is the designation commonly used for the stainless steel grade 17-4 PH, a precipitation-hardening alloy also known by its UNS number S17400. It is a versatile, corrosion-resistant stainless steel that develops high strength through aging and heat treatment, making it suitable for load-bearing components in demanding environments.

Composition and standards

The alloy typically contains chromium in the mid-teens (around 15–17.5%), nickel in the low single digits (roughly 3–5%), and copper in the same general range, with small additions of elements such as niobium or tantalum to stabilize carbides. Carbon content is kept low (commonly under 0.07%). It is standardized as UNS S17400 and is specified in standards that cover age-hardenable stainless steels, such as ASTM listings for 17-4 PH alloys. The designation 174PH is often used interchangeably with 17-4 PH in catalogs and specifications.

Properties and heat treatment

17-4 PH exhibits high strength after precipitation hardening, combined with good corrosion resistance for a stainless steel. Its mechanical properties improve significantly through aging heat treatment, typically following a solution-treatment step. The material can be worked in the solution-treated condition and is capable of forming complex shapes, gears, fasteners, and fittings, with strength tailored by the aging temperature and time. The alloy is generally machinable and weldable, though welding can require proper procedure control and post-weld heat treatment to maintain properties.

Applications and processing

174PH is widely used in aerospace, chemical processing, oil and gas, and medical device industries. Common components include fasteners, valves, fittings, gears, and high-strength structural parts. Availability spans bars, forgings, sheets, and plates produced by various steel mills, with heat-treatment services often available from suppliers to achieve target properties.

See also

17-4 PH stainless steel, precipitation-hardening stainless steels, UNS S17400, ASTM A564.